The standard piano keyboard configuration developed in Europe centuries ago has become accepted as a practical compromise solution to the complex problem of interfacing the human hand to a music machine. Its main advantages of relative simplicity, universal acceptance, standardization, and mass-producibility are gained in a tradeoff which burdens the pianist with some disadvantages. Due to the radical difference of the fingering in each of the twelve key signatures, piano students are faced with the formidable task of memorizing the numerous fingering patterns required for scales, chords and arpeggios, to say nothing of musical scores. Even accomplished pianists favor certain key signatures and avoid others. Ironically, in transposing, the smallest step (a semitone) is the most difficult due to the extent of the fingering differences. Another disadvantage is the narrow separation provided between the black keys for playing the white keys: the standard 1.27 cm (0.5") separation poses difficulty for those with large fingers. Because of the major differences between the black and the white keys in size, shape, elevation, distance from the player, etc., and the mismatch resulting from the shape of the human hand, piano playing technique becomes an odd assortment of playing regions and hand/finger positions that differ from finger to finger.
There are three main key playing regions: (1) the full width portion of the white keys, (2) the narrow portion of the white keys (between the black keys), and (3) the black keys. Each digit of the hand relates differently to each of these three regions; for example, the thumb strongly favors (1), usually requires forward hand movement to reach (2) and has much difficulty with (3), and the small finger also tends to favor (1) due its short length and limited range. Using the thumb or small finger for black keys usually requires a twisting of the wrist. In general the fingers all must adapt to all three positions since the white keys are played at (1) sometimes and at (2) at other times, depending on the playing context. The fingers must be trained to compensate for the different "touch" due to the differences in distance from the key pivot, leverage, relative key mass location and dynamics, etc., not only between the white and black keys but also between the alternative playing regions (1) and (2) on the white keys.
Since region (1) is along a different axis considerably closer to the player as well as lower than the black key region (3), either a backward hand movement or a finger curl is required for a finger to play a (3)-(1) sequence, thus requiring a great deal of arm, hand and finger movement and causing considerable playing inconvenience and fatigue.
In the overall compromise, to accommodate the black keys the nominal white key width (i.e. the center to center spacing) is made 22.9 cm (0.9"), whereas 1.9 cm (0.75") would be adequate for monolithic keys, particularly if the finger shape and position could be kept more natural and consistent and the key shape were enhanced.
Many musicians would welcome an improved musical keyboard system which is more ergonomic, i.e. better matched mechanically to the human hand and which would permit the same fingering in all key signatures while retaining the generally accepted requirement of being able to span at least an octave comfortably with one hand. Furthermore it would be desirable to be able to play practically any of a large number of possible note groupings as chords or arpeggios within the octave without awkwardness or discomfort to the fingers.
A unified fingering system is defined as one in which all of the keys would be of identical shape and disposed in a uniform array: a chromatic scale could be played using one thumb (or finger) with only a linear movement of the hand in an X-axis direction along the keyboard, as opposed to the forward and back (Y-axis) and up and down (Z-axis) finger and hand motion required to play the black and white piano keys due the relative offset of their playing surfaces in both the Y-axis and the Z-axis. For purposes of the present disclosure the axis convention is selected such that a plan view of the keyboard is expressed in X and Y co-ordinates or columns and rows.
A single row keyboard with uniform keys suffers from two main disadvantages: (a) if the keys are made to have adequate width, the span available with one hand is limited to much less than an octave, and (b) a single linear array is poorly matched to the arcuate pattern formed by the different lengths of the thumb and fingers of the human hand.
Another drawback of conventional piano keys is that the white keys, being rectangular, are closely spaced all the way to the end so that a finger extending past a key edge is likely to play an unwanted adjacent note.